There is a significant activity in the oilfield today to perform operations such as frac work in shales or deepwater to provide a path for hydrocarbons stored in the formations to be produced. Horizontal wells are drilled and divided into multiple zones within the horizontal and deviated sections of the well. Each zone is frac'ed individually to allow for the production of hydrocarbon. Each zone may further comprise a packer used to isolate and create multiple zones downhole and a sliding sleeve.
Normally, a sliding sleeve controls the flow of fluid from the inside of the production pipe into the reservoir or from the reservoir to the inside of the production pipe. For frac applications, the sleeve is adapted with a seat which is attached to the inner sleeve. The seat allows for a ball pumped from the surface into the well to be seated on the seat, sealing the well below the ball. The seats may have multiple diameters allowing for multiple diameter balls to be deployed in a well. A large seat will allow a smaller ball to pass by the seat and reach a seat at a lower zone in the well.
Once the well is frac'ed the seats and the balls in the well are milled out to allow production to occur. The costs associated with pumping balls in wells and the cost and time associated with milling the balls and seats are quite high. Also, there is a limit to the number of balls and seats that can be used due to the size of the balls and the potential that a small ball may not go through a seat. This limitation reduces the options related to the number of sliding sleeves that can be deployed in a well hence limiting the number of production zones that can be created in a well.
In addition, there cannot be any control of the hydrocarbon flow in the laterals because no hydraulic lines or electrical lines can be deployed from the main bore into the laterals so that all control of each lateral has to be done from far away in the main bore.